Keyframe arrangement



April 13, 1965 c. w. ANDERSEN KEYFRAME ARRANGEMENT Filed Feb. 23, 1962 Filed Feb. 23, 1962, Ser. No. 175,106 Claims. ((1 84-432) This invention relates generally to musical instruments such as pianos and the like, and more particularly to the framework for supporting the key levers of a piano keyboard.

In the past, it has been common practice to assemble a keyframe by positioning the several rails over the slats or crosspieces and thereafter driving screws into the slats to engage the rails and unite the parts into a rigid framework. Occasional difiiculties have arisen due to the screws interfering with subsequent planing and shaping of the rails; but more importantly the screwed attachment of the balance rail has rendered repositioning of that member both troublesome and inconvenient after the keyframe has been mounted in a piano case.

It is, therefore, an important object of the present invention to provide a new and improved keyframe arrangement which overcomes the limitations of the prior art.

Another object of the invention is to provide a keyframe which incorporates an interfitting attachment between the crosspieces and at least some of the rails.

Still another object of the invention is to provide a keyframe which can be shaped in woodworking machines without danger of damage to the tools.

And still another object of the invention is to provide a keyframe arrangement that facilitates adjustment in the position of the balance rail.

Additional objects and features of the invention pertain to the particular structure, materials and arrangements whereby the above objects are attained.

A structure in accord with the invention includes a first wooden rail, a second wooden rail disposed parallel .to and spaced apart from the first rail, a plurality of wooden crosspieces afiixed to the first and second rails pieces to fix the third rail rigidly to the selected crosspieces, and means adjustably mounting the third rail to the crosspieces away from the temporary connecting structures whereby to permit regulation in the position of the third rail relative to the remainder of the framework'upon removal of the connecting structures.

Inorder that the principle-of the invention may be readily understood, a single embodiment thereof is shown in the accompanying drawing wherein:

FI G; 1 is a perspective view of a keyframe constructed in accordance with the invention;

FIG. 2 is a top plan View of the keyframe of FIG. 1; FIG. 3 is a perspective view of the outside rails and one of the crosspieces, the parts being shown in their disassembled state in order to reveal the mortise and tenon connection which is contemplated by the invention; FIG. 4 is an enlarged view taken along the line 4-4 of FIG. 2 showing the connection of the crosspieces and the several rails; and

FIG. 5 is a view similar to the showing of FIG. 4 but illustrating repositioning of the balance rail after removal of the temporary connecting structures.

Referring now in detail to the drawing, specifically to FIGS. 1 and 2, a keyframe indicated generally by the numeral will be seen to comprise a front rail 12, a

United States Patent 0 Patented Apr. 13, 1965 back rail 14, a balance rail 16 and a suitable number of crosspieces or slats 18. The rails 12, 14 and 16 take the form of elongated members having substantially rectangular cross-section whereas the slats 18 possess a similar cross-section but appreciably shorter length. Furthermore, it has proved advantageous to fashion the front rail 12 and the balance rail 16 from a dense, tight grained hardwood such as maple, while the back rail 14 and the slats 18 may be fabricated from poplar or some other available wood.

In accordance with an important feature of the invention, the slats 18 are connected to both the front rail 12 and the back rail 14 in interfitting relationship. With specific reference to FIG. 3, the back rail 14 is fashioned with mortises 20 opening from a common lateral edge. Similarly, the front rail 12 is fashioned with mortises 22 which open from a common lateral edge of that rail in individual alignment with the mortises 20. Each of the slats 18 is provided with cooperatively shaped tenons 24 at its opposite ends; and in accordance with the illustrated embodiment, the tenons 24 are coated with a suitable adhesive material prior to their insertion in the mortises 20 and 22. It is to be recognized that, after this adhesive material has set, the front rail 12, the back 'rail 14 and the slats 18 are united into a solid framework.

Considering FIGS. 1 and 4, the balance rail 16 will be seen disposed parallel to both the front rail 12 and the back rail 14 overlying the slats 18; and after the balance rail 16 has been properly positioned in the course of assembling the keyframe 10, holes are bored through the balance rail 16 perpendicular to the plane of the keyframe and into the slats 18 therebeneath in order to receive cylindrical dowel pins 26 in mounting the balance rail 16 to the slats. The dowel pins 26 are fabricated from a suitable wood and coact with both the slats and the balance rail with a wood-to-wood contact therebetween. If desired, the balance rail 16 may be rabbeted to receive the several crosspieces or slats 18. I Since the keyframe 10 may be subjected to rough handling and'treatment in subsequent planing and shaping of the several rails, particularly the'balance rail and the back rail, it has proved important to provide connecting structures acting between the balance rail 16 and at least some of the crosspieces 18 in order to maintain the balance rail in connection with remainder of the framework. In addition, these connecting structures have been made temporary so that they may be removed after the shaping and planing operations soas to permit adjustment in the position of the balance rail for purposes to be brought out more fully hereinafter.

Specifically, the temporary connecting structures include adhesively connected surface portions 28 acting "between abutting surfaces of the opposite ends of the balance rail and the underlying'slats as is particularly well shown in FIG. 2. As is shown in FIG. 3, the surface portion 28 of a slat 18 starts at the 'outer edge thereof-to extend inwardly approximately one-half the width of the slat, the surface portion 28 having a length corresponding to the width of the balance rail 16. Any suitable adhesive material may be used in connecting the abutting surface portions 28 of the balance rail 16 and the slats 18 underlying the ends of the balance rail.

After the keyframe 10 has been assembled and after both the front and balance rails have been subsequently planed and moulded to the desired shape, saw cuts are made along the lines indicated by the numeral 30 in FIG. 2 whereby to sever the temporary connecting structures from the remainder of the framework.

This severance of the temporarry connecting structures permits the balance rail 16 to be pried apart from the slats 1-8 as is shown in FIG. 5. The dowel pins 26 movement while' permitting this vertical repositioning of the balance rail.

After the balance rail l6 has been pried apart from the slats 18, paper shims, not shown, may be inserted between the balance rail and the crosspieces in order to regulate the height of the key levers'which" are mounted thereon. When it is desiredtoregulate the height of the natural note keys, the shims are placed beneath the front edge 32 of the balance rail; and when it is deisred toregulate the height 'of the sharp note keys the shims are placed beneath the back edge 34 of the balance rail. With the shims properly positioned, the balance rail is urged toward the slats to clamp the shims in place. Ordinarily, this repositioning of the balance rail takes place after the keyframe has been mounted in the piano case.

From the foregoing descriptions, itis evident that the instant invention provides a keyframe which is completely assembled without use of metal parts and which is, therefore, amenable to being shaped in woodworking machines without the danger of damage to the tools; In addition, it is evident that the keyframe of the invention facilitates adjust-ment inthe position of the balance railafter'the woodworkin-goperations have been performed and after the keyframe has been mounted in'a piano case; Because of I these considerable advantages, it isrecognized that the keyframe ofthe invention will find utility in key-operated musical instruments other than pianos, asfor example-in organs. a

Hence-thespecific example herein shown and described should be considered as illustrative only; Various changes'in structure may; of course, occur to those skilled in the art; and such changes are to be understood as forming a part of this inventioninsofar as they fall within the truespirit and scope of the appended claims.

The invent-ion is claimed as follows:

1. A- framework for supporting the key levers of a piano keyboard, said-framework comprising; a first elongated wooden member having a first-plurality of mortises opening from a common vlateral edge; a second elongated wooden member I disposed parallel to and spaced apart from said first member, said second member having a second plurality of mortises correspondingin number to said first mortises and opening froma common lateral edge of said second member inindividual alignment with said firstmQrtises; a'plurality; of wooden jcrosspieces having tenons fashioned at the ends-thereof, said crosspieces beingdisposed to bridge the spacebetwen said elongated members with said tenons received-in said mortises; a thirdelongated wooden member disposedparal-lel to said first-andsecond members overlying said crosspieces; and straight-walled wooden elements disposed-perpendicular to said third m'ember andto said crosspieces and engaging saidthird member .and said crosspieces for vertically slidably' adjustably. mountingsaid third member to saidcrossp e i L i I -2. A framework for supporting the key levers offa pianokeyboard, said framework comprising: 'afirst elongated wooden member'having afirst plurality .ofmor- ,tises.. opening-from a common lateral edge; a? second elongated wooden member disposed parallel to and spaced apart from said first member, said member having a. second plurality ofmortises corresponding in number to; said first mortises and opening'froma common lateraledge of said secondmember inindividual alignment withsa-id first mortises;.a plurality of wooden crosspieces having tenons fashioned at the ends thereof, said crosspieces being disposed to bridge the space between said elongated members with said tenons received in said mortises; adhesive means acting between said mortises and said tenons; a third elongated wooden member disposed parallel to Said first and second members overlying said crosspieces; and

straight-walled wooden elements disposed perpendicular to said third member and to said crosspieces and engaging said third member and said crosspic-ces for vertically s'lid'ably adjustably mounting said third member to said orosspieces.

3. A framework for supporting the key levers of a piano keyboard, said framework comprising: a first elongated wooden member having a first plurality of mortises opening from a common lateral'e'dge; a second elongated wooden member disposed parallel toand spaced apart from said first member, said second member having a second plurality of mortises corresponding in number to said first mortises and opening from a common lateral edge of said second member in individual alignment with said first mortises; a-p'lurality of wooden crosspieces, having tenons fashioned at the ends thereof, said crosspieces beingdisposed to bridge the space between said elongated members with said tenons received in said mortises; a third elongated wooden member disposed parallel to said first and second members overlying said crosspieces; and means slidably adjustably mounting said third member to said crosspieces including a plurality of straight-walled wooden pins cooperatively received in holes fashioned in said cros'spieces and in said third member, said pins coacting with said third member with wood-to-wood contact therebetween.

4. The method of manufacturing. a-piano' keyframe which comprises the steps of: making a rail and cooperating cr-osspieceswith discardable portion-s; assembling said rail and said crosspieces with rigid connections between the respective discardable portions thereof and with perpendicular sliding connections away from said portions whereby to facilitate shaping and other processing of said keyframe; machining said assembled rail and crosspices in continuation of the rigid connections at withperpendicular sliding connections away from said portions whereby to facilitate shaping and other processingof said keyframe; machining said" assembled rail and "crosspieoes in continuation of the adhesive connections athsaid discard-able portions, and removing said discardable portions whereby to permit regulation in the vertical position of saidrail'relative to 'said'crossp-ieces.

' References Cited in the file of this patent I UNITED STATES PATENTS 477,830 Whitney 1113628, 1892 480,014 Hawes Aug. 2, 1892 483,378 Fuller Sept;;27-, I892 3,072,005 

4. THE METHOD OF MANUFACTURING A PIANO KEYFRAME WHICH COMPRISES THE STEPS OF: MAKING A RIAL AND COOPERATING CROSSPIECES WITH DISCARDABLE PORTIONS; ASSEMBLING SAID RAIL AND SAID CROSSPIECES WITH RIGID CONNECTIONS BETWEEN THE RESPECTIVE DISCARDABLE PORTIONS THEREOF AND WITH PERPENDICULAR SLIDING CONNECTIONS AWAY FROM SAID PORTIONS WHEREBY TO FACILITATE SHAPING AND OTHER PROCESSING OF SAID KEYFRAME; MACHINING SAID ASSEMBLED RAIL AND CROSSPIECES IN CONTINUATION OF THE RIGID CONNECTIONS AT SAID DISCARBABLE PORTIONS; AND REMOVING SAID DISCARDABLE PORTIONS WHEREBY TO PERMIT REGULATION IN THE VERTICAL POSITION OF SAID RAIL RELATIVE TO SAID CROSSPIECES. 